(a) Field of the Invention
The present invention relates to a method of beamforming of a communication node and a 3D antenna array included in a communication node which performs wireless communication.
(b) Description of the Related Art
To improve a data rate and quality of a communication link in a mobile communication network and a wireless local area network, a closed-loop spatial multiplexing (CL-SM) scheme or a closed-loop beamforming (CL-BF) scheme using multiple input multiple output (MIMO) antennas and channel state feedback information on those antennas, has been applied. The CL-SM is a scheme of transmitting multiple data streams in parallel using the MIMO antennas. The CL-BF is a scheme of forming a beam in order to improve signal quality using the MIMO antennas. The CL-SM scheme and the CL-BF scheme have a commonality in aspect of following; a receiving node measures a channel state of a radio link to obtain an appropriate weight value for each MIMO antennas and returns the obtained weight value to a transmitting node, and the transmitting node transmits data signals precoded by the feedbacked weight values.
The traditional beamforming transmission scheme has been applied to a traffic channel or a packet for transmitting data in a wireless communication network. Communication nodes should configure a wireless link to transmit and receive data among nodes. A control signaling process of exchanging control information between the communication nodes is required for the link configuration. Therefore, communication coverage that two nodes can reach each other may be defined based on a coverage area of a control channel or a control packets, and a CL beamforming scheme is needed for the control channels/packets as well as traffic channels/packets in order to extend the communication coverage.
Further, the traditional wireless communication network is based on the assumption that communication is made between a fixed base station (BS) and mobile terminals, in which the base station may include a one-dimensional antenna array which radiates a signal in a specific horizontal direction. Another base station may include a two-dimensional planar antenna array in a horizontal/vertical direction to form a horizontal and vertical beam. However, in the wireless communication network in which all the communication nodes, the base stations and the mobile terminals, move, all the communication nodes need to include an antenna array to configure a beam in any horizontal and vertical direction. In this case, there is a need to develop an appropriate beamforming transmitting/receiving scheme.
However, to form a precise beam in any horizontal and vertical direction using a three-dimensional antenna array, a larger number of antennas than the number of antennas included in the one-dimensional or two-dimensional antenna array need to be used. The communication nodes should perform channel measurement, weight calculation, weight feedback, and beamforming on the large number of transmit and receive antennas among nodes. Overhead and complexity for these processes are large and high.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.